Protected Resources

Olive Ridley

While many of the nesting populations along the Pacific coast of Mexico have disappeared, an estimated 450,000 turtles still nest in arribadas at La Escobilla. Costa Rica supports an estimated 600,000 nesting olive ridleys between its two major arribada beaches Nancinte and Ostional. Other countries in the Pacific hosting nesting populations producing between 100 and 2,000 nests per year include Guatemala, Honduras, El Salvador, Australia, Brunei, Malaysia, Indonesia, and Vietnam.

Physical Description

The carapace (shell) is round in shape and its length can range from 24-28 inches.

They are named for the olive green color of their carapace and have a light greenish-yellow plastron (underside).

Olive ridleys have five vertebral scutes (large scales) that run down the middle of the carapace. They differ from other sea turtle species by having anywhere from 4 to 9 elongated costal scutes along each side of the vertebral scutes.

Diet

This species eats a wide variety of things including mainly fish, salps, and invertebrates, along with some mollusks, crustaceans, algae, bryozoans, and even fish eggs. With such an array of prey items, olive ridleys can be found feeding in a variety of habitats including deep water, pelagic habitats, soft bottom, and shallow benthic waters.

Lifespan

Unknown

Reproduction

Olive ridleys are extremely unique from all other sea turtle species when it comes to their nesting behavior. While most sea turtles emerge individually to deposit their eggs, olive ridleys nest en masse, with as many as 50,000 turtles sharing a 1 mile long beach over just a few days. At a primary nesting beach, La Escobilla, Mexico, more than 1 million nests can be laid in a year using this 'safety in numbers' approach. These mass nesting events are known as arribadas (Spanish for 'arrival') and appear to follow a lunar cycle. Sexual maturation for this species takes a relatively short 11-16 years and females will then nest every 1 to 2 years.

A female olive ridley will only nest 2 to 3 times per nesting season and lay about 105 eggs each time. With so many turtles sharing a small space during arribada, nests from other females are often dug up and destroyed by fellow nesters.

The average incubation time for this species is around 55 days. When finished laying, most other sea turtles cover their eggs with sand using their rear flippers to pack it in firmly on top of their clutch. Since the olive ridley is so relatively light, however, they do not have the power to use their rear flippers in this way; instead, they use their whole bodies, beating the sand down with their plastrons after covering the eggs.

Distribution

In the Pacific Islands region, they do not nest anywhere under U.S. jurisdiction. Their Pacific nesting grounds include the Pacific coasts of Mexico and Central America. However, as a highly migratory species, they are encountered in U.S. waters as they travel between nesting and foraging habitats.

Potential Threats

Incidental catch by commercial fishing vessels.

Entanglement in marine debris.

Boat collisions.

Historically, populations of olive ridleys nesting in Mexico have been threatened by intensive egg removal and direct harvest for the turtle leather trade. Intense protection by the Mexican government has mitigated those threats substantially.

Current Management Issues

The Protected Resources Division (PRD) has the responsibility to implement the Endangered Species Act (ESA). The division is tasked with the recovery of all ESA listed species, including all five species of sea turtle that occur in the region. This includes writing and implementing species recovery plans and permitting/authorizations for important fishery interactions issues.

Public outreach and education.

Partner with state and local governments and other entities to successfully manage endangered species and provide funding for research and conservation.